<?php

class __GooglePageRankChecker {

    //settings - host and user agent
    const GOOGLEHOST = 'toolbarqueries.google.com';
    const GOOGLEUA = 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.6) Gecko/20060728 Firefox/1.5';
    
    //convert a string to a 32-bit integer
    function StrToNum($Str, $Check, $Magic) {
        $Int32Unit = 4294967296; // 2^32
        

        $length = strlen ( $Str );
        for($i = 0; $i < $length; $i ++) {
            $Check *= $Magic;
            //If the float is beyond the boundaries of integer (usually +/- 2.15e+9 = 2^31), 
            //  the result of converting to integer is undefined
            //  refer to http://www.php.net/manual/en/language.types.integer.php
            if ($Check >= $Int32Unit) {
                $Check = ($Check - $Int32Unit * ( int ) ($Check / $Int32Unit));
                //if the check less than -2^31
                $Check = ($Check < - 2147483648) ? ($Check + $Int32Unit) : $Check;
            }
            $Check += ord ( $Str {$i} );
        }
        return $Check;
    }
    
    //genearate a hash for a url
    function HashURL($String) {
        $Check1 = StrToNum ( $String, 0x1505, 0x21 );
        $Check2 = StrToNum ( $String, 0, 0x1003F );
        
        $Check1 >>= 2;
        $Check1 = (($Check1 >> 4) & 0x3FFFFC0) | ($Check1 & 0x3F);
        $Check1 = (($Check1 >> 4) & 0x3FFC00) | ($Check1 & 0x3FF);
        $Check1 = (($Check1 >> 4) & 0x3C000) | ($Check1 & 0x3FFF);
        
        $T1 = (((($Check1 & 0x3C0) << 4) | ($Check1 & 0x3C)) << 2) | ($Check2 & 0xF0F);
        $T2 = (((($Check1 & 0xFFFFC000) << 4) | ($Check1 & 0x3C00)) << 0xA) | ($Check2 & 0xF0F0000);
        
        return ($T1 | $T2);
    }
    
    //genearate a checksum for the hash string
    function CheckHash($Hashnum) {
        $CheckByte = 0;
        $Flag = 0;
        
        $HashStr = sprintf ( '%u', $Hashnum );
        $length = strlen ( $HashStr );
        
        for($i = $length - 1; $i >= 0; $i --) {
            $Re = $HashStr {$i};
            if (1 === ($Flag % 2)) {
                $Re += $Re;
                $Re = ( int ) ($Re / 10) + ($Re % 10);
            }
            $CheckByte += $Re;
            $Flag ++;
        }
        
        $CheckByte %= 10;
        if (0 !== $CheckByte) {
            $CheckByte = 10 - $CheckByte;
            if (1 === ($Flag % 2)) {
                if (1 === ($CheckByte % 2)) {
                    $CheckByte += 9;
                }
                $CheckByte >>= 1;
            }
        }
        
        return '7' . $CheckByte . $HashStr;
    }
    
    //return the pagerank checksum hash
    function getch($url) {
        return CheckHash ( HashURL ( $url ) );
    }
    
    //return the pagerank figure
    function getpr($url) {
        $ch = getch ( $url );
        $fp = fsockopen ( self::GOOGLEHOST, 80, $errno, $errstr, 30 );
        if ($fp) {
            $out = "GET /search?client=navclient-auto&ch=$ch&features=Rank&q=info:$url HTTP/1.1\r\n";
            //echo "<pre>$out</pre>\n"; //debug only
            $out .= "User-Agent: " . self::GOOGLEUA . "\r\n";
            $out .= "Host: " . self::GOOGLEHOST . "\r\n";
            $out .= "Connection: Close\r\n\r\n";
            
            fwrite ( $fp, $out );
            
            //$pagerank = substr(fgets($fp, 128), 4); //debug only
            //echo $pagerank; //debug only
            while ( ! feof ( $fp ) ) {
                $data = fgets ( $fp, 128 );
                //echo $data;
                $pos = strpos ( $data, "Rank_" );
                if ($pos === false) {
                } else {
                    $pr = substr ( $data, $pos + 9 );
                    $pr = trim ( $pr );
                    $pr = str_replace ( "\n", '', $pr );
                    return $pr;
                }
            }
            //else { echo "$errstr ($errno)<br />\n"; } //debug only
            fclose ( $fp );
        }
    }
    
    //generate the graphical pagerank
    function getPageRank($url, $width = 40, $method = 'style') {
        if (! preg_match ( '/^(http:\/\/)?([^\/]+)/i', $url )) {
            $url = 'http://' . $url;
        }
        $pr = getpr ( $url );
        $pagerank = "PageRank: $pr/10";
        
        //The (old) image method
        if ($method == 'image') {
            $prpos = $width * $pr / 10;
            $prneg = $width - $prpos;
            $html = '<img src="http://www.google.com/images/pos.gif" width=' . $prpos . ' height=4 border=0 alt="' . $pagerank . '"><img src="http://www.google.com/images/neg.gif" width=' . $prneg . ' height=4 border=0 alt="' . $pagerank . '">';
        }
        //The pre-styled method
        if ($method == 'style') {
            $prpercent = 100 * $pr / 10;
            $html = '<div style="position: relative; width: ' . $width . 'px; padding: 0; background: #D9D9D9;"><strong style="width: ' . $prpercent . '%; display: block; position: relative; background: #5EAA5E; text-align: center; color: #333; height: 4px; line-height: 4px;"><span></span></strong></div>';
        }
        
        $out = '<a href="' . $url . '" title="' . $pagerank . '">' . $html . '</a>';
        return $out . " PageRank = " . $pr . " /10<br>";
    }

}